Edward H. Jacob, A study of mushrooms and mushroom spawn (1914)
“ Growers who are obliged to purchase manure at a distance, pay the freight on it and employ competent men to handle and care for the mushroom-growing plants, estimate the cost of producing mushrooms at 15 to 25 cents per pound.Those who grow mushrooms for pleasure, and have their own stables, or get manure from a neighboring stable, are at very little expense and could grow mushrooms at less than half the above cost. ”
